You wouldn't guess it from the actions of the Ulster Unionist Party and the Democratic Unionist Party leadership, but the Union is safe.

It is safer than it has ever been in living memory. The recent Ipsos Mori opinion poll bore witness to the great achievement of the Belfast Agreement – the vast majority right across our entire community are content with the current constitutional settlement.

They are supportive of Northern Ireland's place within the United Kingdom.

This should, then, be a time for pro-Union politics to be reaching out with confidence and with generosity.

Vast swathes of voters who do not presently vote for either the UUP or the DUP are open to be persuaded to vote for an inclusive, civic, pro-Union politics.

But, instead of reaching out to such voters, we are seeing the UUP and DUP act defensively and circle the wagons.

Combining the UUP and DUP votes – the strategy chosen by both parties for the Mid-Ulster by-election – sells pro-Union politics and Northern Ireland itself short.

It entirely ignores the vast and growing numbers who do not vote, regarding both parties as failing to speak to, or for, them.

It ignores voters from a nationalist background (ironically, a majority of SDLP voters and a significant minority of Sinn Fein voters), who are content with Northern Ireland's place in the United Kingdom.

Rather than reach out to both groups, the UUP and DUP leadership has opted to retreat into the trenches of tribal politics.

Nor is this a new experiment: it has been tried before and it failed. In the 2010 Westminster elections, the UUP and DUP ran a Unity candidate in Fermanagh and South Tyrone.

The sitting Sinn Fein MP, Michelle Gildernew, was returned and the party went on to increase its share of the vote in the subsequent Assembly elections.

An increased Sinn Fein majority and voters pushed back into the sectarian trenches: this is hardly a successful pro-Union electoral strategy. When the UUP took the decision to support a Unity candidate in the 2010 elections, I and others had grave misgivings.

We were assured that it was a one-off, not to be repeated. This is why no similar arrangement emerged in South Belfast.

In the post-election consultations, I clearly stated that the Unity candidate decision – along with the talks at Hatfield House – had entirely undermined the UUP's attempt to communicate a progressive, pluralist, pro-Union message.

Another critic of the decision was Tom Elliott, who consistently pointed out to UUP audiences that the unity strategy had only increased the Sinn Fein vote.

Repeating this failed strategy – and doing so during the first electoral contest of Mike Nesbitt's leadership – does a disservice to pro-Union politics and to the Belfast Agreement's vision of the new Northern Ireland.

There is nothing progressive about repeating the failed politics of the past; encouraging voters to retreat into sectarian trenches, rather than confidently building support for the Union in a shared Northern Ireland.

That the leadership of the UUP has decided to return to the politics of the past is their choice.

My focus is now on promoting an authentically progressive, pluralist, pro-Union politics, inviting support from across the community for a shared Northern Ireland at ease with its place in the modern United Kingdom.